Self-Guiding Backscattering Immune Transportation of Light in the Visible Range

Qiuyue Zhang,Xun Li

doi:10.1109/jphot.2019.2944928

Abstract

The implementation of topological photonic systems at optical frequency is of great significance for practical applications. In this work, we extend the study of unidirectional transmission to the visible light range with a relatively simple structure. We theoretically demonstrated the existence of self-guiding one-way edge modes at the interface between air and a hexagonal lattice of rods with a layered plasmo-semiconductor-gyroelectric metamaterial as the background medium. The inherent loss in metals can be compensated by the incorporation of the semiconductor layers with optical gain. Our simulation result shows that the self-guiding transmission remains 82% over a distance of about 30 wavelengths. In addition, it renders the light travel on such an interface insensitive to obstacles or impurities either on-purposely introduced or caused by manufacturing imperfections or variations. We show that the power transmission remains around 80% even in the presence of deliberately introduced obstacles. By exploiting the robust self-guiding unidirectional transport feature, we have designed a shape-independent cavity that can tolerate sharp corners in different angles, which eliminates the reflection and relaxes the geometrical constraint in design of integrated photonic devices.

Highlights

Numerous theoretical [1]–[9] and experimental [10]–[16] investigations based on the photonic topological insulators (PTIs) have been widely reported due to their unique feature of backscatteringimmune transmission regardless of the presence of disorders or defects
We theoretically demonstrated the existence of self-guiding one-way edge modes at the interface between air and a hexagonal lattice of rods with a layered plasmo-semiconductor-gyroelectric metamaterial as the background medium
We have studied the self-guiding unidirectional edge modes at the interface of a hexagonal photonic crystal (PC) consisting of rods in a layered plasmo-semiconductor-gyroelectric metamaterial (PSGM), with the semiconductor gain medium introduced in attempt to compensate the metal loss

Summary

Introduction

Numerous theoretical [1]–[9] and experimental [10]–[16] investigations based on the photonic topological insulators (PTIs) have been widely reported due to their unique feature of backscatteringimmune transmission regardless of the presence of disorders or defects. Wu et al [9] studied one-way edge modes in the visible frequencies based on a layered plasmo-gyroelectric structure. By reducing the strength of the on-diagonal elements of the permittivity tensor to increase the Voigt parameter, they managed to raise the bandgap by orders of magnitude. Their approach does not require any complicated geometrical structure. We have studied the self-guiding unidirectional edge modes at the interface of a hexagonal photonic crystal (PC) consisting of rods in a layered plasmo-semiconductor-gyroelectric metamaterial (PSGM), with the semiconductor gain medium introduced in attempt to compensate the metal loss. All simulation results in this work were obtained with the finite element method (FEM)

The Geometric Structure and Material Parameters

Self-Guiding Unidirectional Transmission

Robustness of the Edge Modes and the Geometry-Independent Cavity

Conclusions